VMC WORKSOP CHEM DOUBT

7 Answers

29
govind ·

I feel the answer shud be B..

11
SANDIPAN CHAKRABORTY ·

i also thought it ......

but ans is c

they said in the second case CH2CH3MgBr acts as base so c

29
govind ·

About product Y
In case of alcohols Grignard reagent acts as a base...but here in this question there are two cases either the grignard reagent can attack the carbonyl group or it can attack the the alcohol...

Case I : If it attacks the carbonyl group so the answer given in option B will be formed ..(in this case i aasumed the condition that since the reaction is occuring in the presence of water so it will get converted into alcohol) so it looks like the assumption may be wrong that's why the answer may be C

Case II : If it attacks the alcoholic group then a hydrocarbon will be formed..
RMgBr + R'OH → MgBr(OR') + RH ..

About Product X...
It's just a simple addition of Grignard Reagent ..the it will form a compound (see compound Y in option B)...then intramolecular esterification will occur and cyclic ester will be formed...

Let's see wat others have to say abt the answer...

1
Ankur ·

yup it is definitely C. Product X is clear of course, in Y, with action of H30+ , acid will be formed and acid when formed reacts with Grigenard reagent to give active alkyl group and same acid. There was similar question in Arihant. If any doubt, reply, I'll try to clear.

29
govind ·

@Ankur..in this case Grignard reagent is reacting with the alcohol fromed and not the acid..
that's why the hydrocarbon is fromed see the reaction abv ..i mentioned it there...
Plz correct me if i am wrong

1
Ankur ·

@govind: The initial hydrocarbon contains two functional groups - keto and ester. When hydrolysed by H30+, ester group is readily hydrolysed to give an acid (as it is more prudent to hydrolysis reaction than keto), this hydrolysis gives a dominant acid and ethyl alcohol.
Now, here comes the reaction of GR, with whatever part GR reacts, either the acid or alcohol, it should give an alkane (from EtMgBr --> EtH).
We can never be sure, with what product GR will react, instead when acid and alcohol are in the same reaction, acid tries to surpass the reaction with GR.
Shouldn't it?

29
govind ·

oh ya... sry gt my mistake..carboxylic acid can donate H+ more easily than alchol..u r ryt...

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